With bars that require the driver bolt to be drilled by the user, the setup is necessary to have the tip of the alignment bar started into the coupler when the gimbal carrier is still not started into the housing. That keeps the bar straight. If the bar is not in the coupler as the gimbal bearing is started, the bar end can impact the edges of the coupler. If the bar end is too far into the coupler when the gimbal bearing starts, then the bar will bottom out in the coupler before seating the bearing carrier fully. There is some wiggle room, but it still needs to be done within those parameters.